Transfusion-associated graft versus host disease

Transfusion-associated graft-versus-host disease (TA-GvHD) is a rare complication of blood transfusion, in which the donor T lymphocytes mount an immune response against the recipient's lymphoid tissue.[1] Donor lymphocytes are usually identified as foreign and destroyed by the recipient's immune system. However, in situations where the recipient is immunocompromised (inborn immunodeficiency, acquired immunodeficiency, malignancy), or when the donor is homozygous and the recipient is heterozygous for an HLAhaplotype (as can occur in directed donations from first-degree relatives), the recipient's immune system is not able to destroy the donor lymphocytes. This can result in graft-versus-host disease.

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The incidence of TA-GvHD in immunocompromised patients receiving blood transfusions is estimated to be 0.1 - 1.0%, and mortality around 80 - 90%. Mortality is higher in TA-GvHD than in GvHD associated with bone marrow transplantation, where the engrafted lymphoid cells in the bone marrow are of donor origin and therefore the immune reaction is not directed against them.

The most common causes of death in TA-GvHD are infections and hemorrhages secondary to pancytopenia and liver dysfunction.

TA-GvHD can be suspected from a biopsy of the affected skin, and established by HLA analysis of the circulating lymphocytes. This testing can identify circulating lymphocytes with a different HLA type than the tissue cells of the host.